Two series of cases form the basis for my discussion of treatment of gastrojejunual ulcer following previously performed gastroenterostomy or partial gastrectomy. The first series consists of 301 cases in which operation for gastrojejunal ulcer was performed at the Mayo Clinic. In 186 of these cases the gastrojejunal ulcer had developed after gastroenterostomy, and in 115 it had followed partial gastrectomy. The mean interval between the previous operation and the definitive operation for gastrojejunal ulcer was 11.2 years for those having previous gastroenterostomy and 3.7 years for those having previous gastric resection. Of the 301 patients, 91% were men and 9% women. A history of hemorrhage from the ulcer, or evidence of it, was found in about half of the cases (149), and perforation into the colon was present in 6.5%. The perforation occurred mostly as a complication of gastrojejunal ulcer after gastroenterostomy, 16 of our 20 cases being in